Grid spring assembly



FIG. 1 is a top perspective view of grid spring assembly showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a side elevation view thereof;

FIG. 5 is a front elevation view thereof; and,

FIG. 6 is a bottom perspective view thereof. 

CLAIM The ornamental design for grid spring assembly, as shown and described. 